Gain Enhancement of Planar Antenna Enabled by Array of Split-Ring Resonators

This communication proposes a high-gain bow-tie antenna operating over the frequency band of 5.5-8 GHz. The proposed antenna is comprised of a microstrip-to-slot transition line connected to bow-tie radiators. Seven slabs of split-ring resonator (SRR) unit cells are integrated into the orthogonal plane of antenna substrate to enhance its gain. Each slab consists of 2×7 double-sided SRR unit cells. A prototype of the antenna is fabricated and measured. The results indicate that the reflection coeflicient is better than -10 dB over the frequency band of 3.5-8 GHz. The measured antenna gain varies from 10.2 to 13.8 dBi over a frequency range of 5.65-7.8 GHz. The measured radiation efliciency corresponds to 90% at 7 GHz. The cross polarization is better than -30 dB in the E-plane at 6.5 GHz.